Simplify temporary directory cleanup

Co-Authored-By: Jon Dufresne <jon.dufresne@gmail.com>

Tests/test_file_pdf.py

@@ -162,13 +162,10 @@ class TestFilePdf(PillowTestCase):
 
     def test_pdf_append_fails_on_nonexistent_file(self):
         im = hopper("RGB")
-        temp_dir = tempfile.mkdtemp()
-        try:
+        with tempfile.TemporaryDirectory() as temp_dir:
             self.assertRaises(
                 IOError, im.save, os.path.join(temp_dir, "nonexistent.pdf"), append=True
             )
-        finally:
-            os.rmdir(temp_dir)
 
     def check_pdf_pages_consistency(self, pdf):
         pages_info = pdf.read_indirect(pdf.pages_ref)

src/PIL/IcnsImagePlugin.py

@@ -314,8 +314,10 @@ def _save(im, fp, filename):
         fp.flush()
 
     # create the temporary set of pngs
-    iconset = tempfile.mkdtemp(".iconset")
-    provided_images = {im.width: im for im in im.encoderinfo.get("append_images", [])}
+    with tempfile.TemporaryDirectory(".iconset") as iconset:
+        provided_images = {
+            im.width: im for im in im.encoderinfo.get("append_images", [])
+        }
         last_w = None
         second_path = None
         for w in [16, 32, 128, 256, 512]:
@@ -344,9 +346,6 @@ def _save(im, fp, filename):
 
         retcode = convert_proc.wait()
 
-    # remove the temporary files
-    shutil.rmtree(iconset)
-
         if retcode:
             raise subprocess.CalledProcessError(retcode, convert_cmd)